/*
 * Copyright (C) 2012 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include <unwind.h>
#include <sys/types.h>

// =============================================================================
// stack trace functions
// =============================================================================

typedef struct
{
    size_t count;
    intptr_t* addrs;
} stack_crawl_state_t;


/* depends how the system includes define this */
#ifdef HAVE_UNWIND_CONTEXT_STRUCT
typedef struct _Unwind_Context __unwind_context;
#else
typedef _Unwind_Context __unwind_context;
#endif

static _Unwind_Reason_Code trace_function(__unwind_context *context, void *arg)
{
    stack_crawl_state_t* state = (stack_crawl_state_t*)arg;
    if (state->count) {
        intptr_t ip = (intptr_t)_Unwind_GetIP(context);
        if (ip) {
            state->addrs[0] = ip;
            state->addrs++;
            state->count--;
            return _URC_NO_REASON;
        }
    }
    /*
     * If we run out of space to record the address or 0 has been seen, stop
     * unwinding the stack.
     */
    return _URC_END_OF_STACK;
}

__LIBC_HIDDEN__
int get_backtrace(intptr_t* addrs, size_t max_entries)
{
    stack_crawl_state_t state;
    state.count = max_entries;
    state.addrs = (intptr_t*)addrs;
    _Unwind_Backtrace(trace_function, (void*)&state);
    return max_entries - state.count;
}